Think of your grounding points as boundaries. If you cross a boundary then you
have to do something to the cable such as ground the shields or use
Polyphasors. Typical boundaries would be top of tower, base of tower, and
entrance to shack. Typical things that are done would be to ground shields at
top of tower, bottom of tower, and at shack entrance where any lightning
protection (Polyphasor) would also be located.
In your case you may want to a boundary at the coax switch half way up the
tower and ground all the shields there too.
As for your case, I would ground the shield of the OCF at the base of the tower
where it passed through that boundary. You could avoid that by running the
coax straight to the switch halfway up the tower instead of routing it back to
ground and then back up the tower.
The point is that you work hard to set up these "boundaries" to bleed off a
lightning strike but if you bypass any of them you give a sneak path that
lightning may use to bypass them.
Earl
N8SS
----------------------------------------------------------------------
Message: 1
Date: Thu, 3 Nov 2016 22:58:48 -0400 (EDT)
From: "jcjacobsen@q.com" <jcjacobsen@q.com>
To: towertalk@contesting.com
Subject: [TowerTalk] Feed line grounding
Message-ID:
<744847813.2686980.1478228328356.JavaMail.root@md47.quartz.synacor.com>
Content-Type: text/plain; charset=utf-8
I haven't found anything addressing this, so I give to the collective group:
All feed line shields are grounded at top of tower. A feed line switch is
located about half way up.
The main feed line shield is grounded at tower bottom. Now for the question:
Have an OCF dipole
supported a distance away from the tower from a tree. It's feed line drops
down, runs on the
ground to the tower base and then UP the tower to the switch. Would it be wise
to ground the shield
of this coax to the tower base. OR is this unnecessary?
Thanks in advance.
73 K9WN Jake
------------------------------
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|